1. Field of the Invention
The field of the invention is motion controllers for controlling servomotor devices on loads such as robots or machine tools.
2. Description of the Background Art
Various types of numerical control, programmable controller and other types of controllers are known for controlling servomotor devices. Servomotors are typically driven with an analog velocity output signal, and a resolver or encoder is attached to provide position feedback signals. Changes in position are determined over time to determine actual velocity, which is then compared with commanded velocity to provide a velocity error input to a velocity control loop. The commanded velocity in turn may be the output of a position control loop in which commanded position is compared with position feedback to provide a position error input.
It is also desirable to limit the velocity output command from the position control loop to some predefined maximum value. This velocity limit should also be applied to any velocity feedforward command V.sub.FF.
In a prior motor control system, a proportional-integral regulator was used in a velocity control loop, with a gain factor K.sub.A being applied to a velocity feedforward command input to the velocity control loop. The gain factor K.sub.A affected system response to higher frequency components of the velocity feedforward command, but there was no independently controllable gain factor K.sub.V to affect system response to lower frequency components of the velocity feedforward command. In this prior system, there was only one velocity command input to the velocity control loop.